RU2451711C1 - Method for delayed coking of oil residues - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the field of oil processing. The method includes heating of source raw materials with subsequent formation of secondary raw materials, heating of secondary raw materials in a reaction furnace 2 and their supply to a coking chamber 3, where the coke and steam-liquid coking products are produced, fractionating of the latter in a rectification column 4 with production of gas, benzine, light and heavy gas oils and stillage bottoms of coking, thermal cracking of the heavy gas oil, at the same time the secondary raw materials are formed in an evaporator 1, connected by vapours with the rectification column 4, by mixing of the source raw materials with a part of the heavy gas oil supplied from the rectification column into the evaportator in the form of a recirculate, and formed products of thermal cracking of the remaining part of the heavy gas oil are mixed with stillage bottoms of coking, and the produced mixture is introduced into secondary raw materials prior to supply into the coking chamber 3.

EFFECT: increased overhaul life of a plant.

1 dwg, 2 ex, 2 tbl

Description

The invention relates to the field of oil refining, in particular, to a method for delayed coking of oil residues to obtain petroleum coke and gas oil fractions - raw materials for the production of motor fuel (gasoline and diesel fuel).

A known method of delayed coking of oil residues, in accordance with which the feedstock is heated to a temperature of 270-400 ° C, mixed with vapor-liquid coking products in a distillation column to produce gas, gasoline, light and heavy gas oil and still bottoms (secondary coking feedstock). Secondary raw materials are heated in a reaction furnace to a temperature of 480-510 ° C and subjected to coking in a coking chamber to obtain coke and vapor-liquid coking products (3rd. Sunyaev. Production, refinement and use of petroleum coke. - M .: Chemistry, 1973, p. .102-104).

The disadvantage of this method is the low yield of gasoline and light gas oil: components of the feedstock for producing high-octane gasoline and high-quality diesel fuel.

In addition, this method determines the low turnaround time of the delayed coking unit due to coking of the reaction coils of the furnace due to the ingress of coke particles into the secondary raw materials due to its formation technology, namely by mixing primary raw materials with vapor-liquid coking products, which contain coke particles carried away by liquid-vapor products.

There is a method of delayed coking of oil residues, which consists in the fact that the raw material after heating is fed to the evaporator to form secondary raw materials by mixing with recirculate, the secondary raw materials are heated in a reaction furnace and fed to the coking chamber, where coke and vapor-liquid coking products are formed, fractionation of the latter in a distillation column with the formation of gas, gasoline, light and heavy gas oil and bottoms coking residue. As the recirculate using the bottom residue of coking (RF patent No. 2209826, publ. 10.08.2003, IPC СВВ 55/00).

The disadvantage of this method is the low yield of gasoline and light gas oil - components of the feedstock for producing high-octane gasoline and high-quality diesel fuel, as well as the short overhaul run of the delayed coking unit due to coking of the reaction coils of the furnace, since coke particles get into the secondary raw materials together with the bottom residue carried away by vapor-liquid coking products.

A known method of delayed coking of oil residues, which consists in the fact that the feedstock after heating is sent to a distillation column for mixing with vapor-liquid coking products and recirculate and fractionation to produce gasoline, light and heavy gas oil and bottoms residue (secondary raw materials). The heavy coking gas oil resulting from the fractionation is subjected to thermal cracking, and the cracking products are used as recirculate material. The bottom residue after heating in the reaction furnace is sent for coking in the coking chamber to obtain coke, gasoline, light and heavy gas oil (UK patent No. 1602097, publ. 1981, IPC C10G 53/16).

This technology allows to increase the output of components of motor fuels: gasoline and light gas oil.

The disadvantages of this method are the significant energy costs due to the fact that the thermal cracking products involved in the secondary raw materials significantly increase the thermal power of the reaction furnace for heating the secondary raw materials. In addition, like the previous analogues, the method has a short overhaul due to coking of the reaction furnace coils due to coke particles entering the secondary raw materials together with vapor-liquid coking products.

Closest to the claimed object is a method of delayed coking of oil residues, which consists in the fact that the feedstock after heating is sent to a distillation column for mixing with vapor-liquid coking products and fractionation to produce gasoline, light and heavy gas oils and still bottoms (secondary raw materials). VAT residue is heated in a reaction furnace and sent for coking in the coking chamber. The heavy coking gas oil obtained as a result of fractionation is subjected to thermal cracking, while the cracking products are mixed with heated secondary raw materials before being fed into the coking chamber (ed. Certificate No. 1084286, publ. 07.04.1984, MPK СВВ 55/00).

As in the method according to the previous analogue, this technology makes it possible to obtain a high yield of components of motor fuels: gasoline and light gas oil.

The disadvantage of this method is the short overhaul run of the installation for delayed coking due to coking of the reaction furnace coils due to coke particles entering the secondary raw materials together with vapor-liquid coking products.

The technical result is an increase in the overhaul distance of the installation for implementing the method of delayed coking of oil residues.

This is achieved by the fact that in the method of delayed coking of oil residues, including heating the feedstock with the subsequent formation of secondary feedstock, heating the secondary feedstock in a reaction furnace and feeding it into a coking chamber in which coke and vapor-liquid coking products are formed, fractionating the latter in a distillation column with by producing gas, gasoline, light and heavy gas oil and bottoms coking residue, thermal cracking of heavy gas oil, according to the invention, the formation of secondary raw materials is carried out they are poured in an evaporator paired with a distillation column by mixing the feedstock with a portion of the heavy gas oil supplied from the distillation column to the evaporator as recirculate, and the resulting thermal cracking products of the remaining part of the heavy gas oil are mixed with the bottom residue of coking and the resulting mixture is introduced into the secondary raw materials before feeding into the coking chamber.

The drawing shows a diagram of the installation delayed coking of oil residues by the proposed method.

The delayed coking unit according to the proposed method comprises an evaporator 1, a reaction furnace 2, coking chambers 3, a distillation column 4, a furnace 5.

The method is as follows.

The oil residue (initial primary raw material) is heated to a temperature of 250-350 ° C and served in the evaporator 1, where it is mixed with recycle to form secondary raw materials. Secondary raw materials are heated in a reaction furnace 2 to a temperature of 470-500 ° C and fed to coking in alternately working coking chambers 3. The resulting vapor-liquid coking products are fed through a helmet tube to a distillation column 4 for fractionation to produce gas, gasoline, light and heavy coking gas oils and the bottom residue of coking. Part of the heavy coking gas oil from the distillation column battery in the form of a side stream in an adjustable amount is fed to the evaporator 1 as recirculate for mixing with the primary raw material. The rest of the heavy gas oil is fed into the furnace 5, where it is subjected to traditional thermal cracking at a temperature of 480-530 ° C and a pressure of 20-50 kg / cm ² . The resulting cracking products (gas, gasoline, light gas oil and cracking residue) are mixed with the bottom residue of coking and the resulting mixture is introduced into secondary raw materials before being fed to the coking chamber.

Example 1 (by the proposed method).

At an industrial installation of delayed coking with a capacity of 600 thousand tons / g, tar from West Siberian oil was coked, the characteristics of which are given in Table 1.

The initial (primary) raw material was heated in heat exchangers and in the convection section of the furnace to a temperature of 350 ° C and fed to the evaporator, where heavy coking gas oil in the amount of 10% was fed from the distillation column battery to the raw material. Obtained by mixing the primary raw material with recirculated secondary raw material was heated in the reaction coils of the coking oven to a temperature of 495 ° C.

Steam-liquid coking products were fed through a helium tube to a distillation column, which also received light fractions from the evaporator, in which separation of gas, gasoline, light and heavy coking gas oils and bottoms took place. The obtained heavy coking gas oil was withdrawn from the distillation column in the form of a side stream and fed to a thermal cracking furnace, where it was cracked (the inlet pressure to the furnace was 25 kg / cm ² , the temperature at the furnace exit was 510 ° C). The cracking products were mixed with the bottom residue removed from the bottom of the distillation column at a temperature of 395 ° C, the mixture was introduced into the secondary raw materials heated in the reaction furnace. The resulting mixture was fed into the coking chamber, where coke and vapor-liquid coking products were formed.

The material balance of the process, the technological mode of delayed coking are given in table. 2.

Example 2 (prototype). The same raw materials as in example 1 were heated in heat exchangers and in the convection section of the furnace to a temperature of 350 ° C and fed to the lower part of the distillation column, where it was mixed with vapor-liquid coking products coming from the coking chamber, and separated into gas, gasoline , light and heavy coking gas oils and bottoms (secondary raw materials).

Heavy coking gas oil was cracked in a thermal cracking furnace at a furnace inlet pressure of 25 kg / cm ² and a furnace exit temperature of 510 ° C. The obtained products of thermal cracking of heavy gas oil were mixed with secondary raw materials heated in the reaction coils of the furnace to a temperature of 495 ° C and fed into the coking chamber.

The material balance of the process and the technological mode of coking are given in table 2.

As can be seen from the data presented, the use of the proposed method of delayed coking of oil residues will allow, in comparison with the method of the prototype, to increase the overhaul mileage of the installation for implementing the method of delayed coking by reducing the coking of the coils of the reaction furnace. This becomes possible due to the fact that excluded the ingress of coke particles into the secondary raw materials, as is the case in the method of the prototype. Moreover, the proposed method provides a high yield of gasoline and light coking gas oil.

Table 1 Quality of coking feed - tar of West Siberian oil The name of indicators The value of indicators Density, g / cm ³ 1,025 Coking ability, wt.% 24.0 The content of asphaltenes,% 14.3 Ash content, wt.% 0.22 Sulfur content, wt.% 2.21 Kinematic viscosity, cSt at 80 ° C 5600 at 100 ° C 840

table 2 Technological regime and material balance of coking Examples The name of indicators by the proposed method prototype Loading of the plant for primary raw materials, t / day 2000 2000 Loading of the plant for secondary raw materials, t / day 2200 2400 Recirculation ratio 1,1 1,2 The temperature of the heating of primary raw materials, ° C 350 350 The temperature of the secondary raw materials at the outlet of the furnace, ° C 495 495 Loading of a thermal cracking furnace (heavy gas oil - FR. Above 350 ° C), t / day 402 364 The pressure at the entrance to the cracking furnace, kg / cm ² 25 25 The temperature at the outlet of the cracking furnace, ° C 510 510 The material balance of the process, t / day (% of raw materials) - hydrocarbon gas 234 (11.7) 230 (11.5) - gasoline (fr. C ₅ -180 ° C) 298 (14.9) 290 (14.5) - light gas oil (fr. 180-350 ° С) 748 (37.4) 742 (37.1) - coke 720 (36.0) 738 (36.9) Overhaul mileage 360 200

Claims (1)

A method for delayed coking of oil residues, including heating the feedstock with the subsequent formation of secondary raw materials, heating the secondary raw materials in a reaction furnace and feeding it into a coking chamber, in which coke and vapor-liquid coking products are formed, fractionating the latter in a distillation column to produce gas, gasoline, and light and heavy gas oil and bottoms coking residue, thermal cracking of heavy gas oil, characterized in that the formation of secondary raw materials is carried out in the evaporator, is connected in pairs with a distillation column by mixing the feedstock with a portion of the heavy gas oil supplied from the distillation column to the evaporator as recirculate, and the resulting thermal cracking products of the remaining part of the heavy gas oil are mixed with the bottom residue of coking, and the resulting mixture is introduced into the secondary raw material before feeding into the coking chamber.